Folding mine-transit.



Pateniad June 27, I899.

7////////////////////////// l R I y////// mm 7////// J. A. BIRSFIELD.

FOLDING MINE TRANSIT.

Application filed Feb 2, 1899.)

(No Model.)

THE Nonms PEYERS 00.. PHOTO-L|THO.. WASHINGTON, o. c.

UNITED STATES PATENT FFICE.

.IULES A. BIRSFIELD, OF DENVER, COLORADO.

. FOLDING MINE-TRANSIT.

SPECIFICATION forming part of Letters Patent No. 627,638, dated June 2'7, 1899.

Application filed February 2, 1899. Serial No. 704,217. (No model.) I

T at whmn it may concern.-

Be it known that I, J ULES A. BIRSFIELD, a citizen of the United States, residing at Den- 'Ver, county of Arapahoe, and State of Colorado, have invented a new and useful Improvement in Pocket-Transits, of which the following is a full specification.

The object of this invention is to provid an instrument superior and more reliable than any herein mentioned or known to myself and i sighted upon the object and then the reading of the needle taken, and when used as a hand instrument two observers were required, one

to sight the instrument on the object whose bearing was to be taken and the other to take a simultaneous reading of the needle. simultaneous sighting and reading of a compass can also be attained by an instrument known as a prismatic compass, but it'suse is limited, because said instrument will only take sights on or near a level with the instrument, and the Weight of the needle is greatly increased and its accuracy impaired by carrying a large circular card. Again, simultaneous sighting and reading of a compass can be obtained and the readings of both vertical and horizontal angles taken by an instrument known as .Bruntons pocket-transit, patented September 18, 1894:, No. 526,021; but its accuracy is impaired and only indiiferent results can be obtained when taking horizontal readings, because the needle of a magnetic compass has no substantial 'bearin g, said needle being mounted on a steel point constantly swinging, and is easily attracted out of its course, according to location of an observer When using said instrument, such as being near mineral (iron) deposits, machinery, or there being a storm, causing electricity in the air. 7 r

So far as I am aware no pocket instrument The cle of the compass.

I designate my device a pocket-transit, having made the instrument small and light enough to be carried in the pocket, and dispense with the use of the Jacobs-staff or tripod.

The instrument comprises a dust-proof casing containing a magnetic compass, a bubbletube, the combination of an adjustable mirror suitably attached to one of the two adjustable folding sights, said sights suitably hingedto cross-bars, said cross-bars and an arm terminating in a Vernier suitably and substantially attached to an axis, the whole rotating by the axis in a bushing, which is cement ed substantially in center of glass cover of compass-casing.

I attain the object of my invention by mechanism illustrated in the accompanying drawings, in which in the figures like parts are similarly designated.

Figure'I is a top view of entire instrument; Fig. II, a vertical and longitudinal section of said instrument on the line A B of Fig. I, full lines showing instrument when used, first, in taking courses withthe needle, and, second, when making a straight line from standingpoint fore and aft, dotted lines of the folding adjustable sight and mirror showing the in strument when used for both horizontal and verticle angles; Fig. III, a vertical section on the line C D, showing a view of the sight provided with sight-line; Fig. IV, a horizontal section on the line E Fin dotted lines of Fig. II, being an enlarged view of the adjustable folding sight provided with adjustable mirror.

A is the casing, which may be of any material ofappropriate character to receive the needle I) of a magnetic compass, said needle being mounted in the usual manner on a steel point 0 and provided with a locking-lever d, which, as here shown, ezitends to the casing at point e and may be operated with a thumbpiece f, said thumb-piece .projectingthrough the casing.

g is the degree-circle of the compass, suitably divided and subdivided, the drawing in Fig. I showing the circle divided in multiples of five.

h is the cover of the casing, which is, as usual in a compass of glass, suitably and substantially attached to casing, and i is the bubble-tube, commonly known as a level, suitably and substantiallymounted to bottom of casing and parallel to zero-points of the degreecircle g.

j is the bushing 0r bearing cemented or otherwise suitably and substantially mounted in center of glass cover it, said bushingj receiving the axis 70, which is provided below the glass cover with the arm m, the said arm terminating in the vcrnier n and extending to the degree-circle g.

0 and p are the cross-bars, suitably and substantially attached to the axis 7.: above the glass cover 71., and provided at opposite ends and suitably hinged thereto are the adjustable folding sights o and s, the said sight .9 provided with the sight-line l, which may be of any suitable material commonly known to be in use, as horsehair, and the sight 1' provided with the grooves u and i), said grooves receiving the adjustable mirror Z.

Some of the uses of this instrument may be stated as follows:

First. The instrument, as shown in Fig. I of drawings, may be used the same as any ordinary compass, the reading taken with the needle.

Second. By placing the folding sights rand s at right angles with the top of the casing, and the. mirror adjusted as indicated in full lines in Fig. II of drawings and the instrument heldfirmly in two hands in ahorizontal position at about the height of the eyes, an observer by looking directly through the opening of sights s and 0 will see an object before him and at the same time in the mirror reflected an object behind, making a straightlinewithout any mechanical movements or adjustments of specified instrument.

Third. By placing the folding sight 3 again at right angles, as indicated in full lines, and the folding sight 0' approximately at about one hundred and thirty-five degrees from the top of the casing and the mirror adjusted as indicated in dotted lines in Fig. II of drawings and holding the instrument firmly at about the height of the waist an observer by looking directly down in the mirror will see the object reflected therein in front of him. The instrument may be thus accurately sighted at any object by bringing it in line with the sight-line 15 and center of mirror, and at same time the Vernier reading may be taken accurately by the same observer. Holding thus the instrumentin one hand and turning with the other the combination of'sights, mirror, and Vernier within the axis courses may be taken to objects horizontally at almost any angle and the reading again taken.

Fourth.v To take vertical angles, the instrument is held edge up at about the height of the eyes, the level showing zero-points of degree-circle to be horizontal, sights and mirror adjusted the same as in taking horizontal angles. A11 observer can take or make in same manner courses to objects vertically above or below the horizontal.

Fifth. By varying the position of the folding sight 0' to any angle suitable, mirror adjusted as indicated in dotted lines of Fig. II of drawings, courses may be taken to objects situated at any angle above or below the horizontal.

Other uses of this instrument will readily suggest themselves to those skilled in the art of surveying; but its general purposes and usefulness as specified are deemed sufficient, and I therefore pray that Letters Patent be granted to me.

I claim as my invention 1. In an instrument of the character described, the combination of the needle-compass, the level or bubble-glass, the Vernier arranged on a central axis, and the folding or hinged sight-s, one of said sights having a sliding mirror adapted to be projected beyond the normally upper end of said sight, and retractible to permit of the folding of said sight, substantially as specified.

2. In an instrument of the character dcseribed, the combination of the needle-compass, thebubble-glass, the parallel cross-bars, the axis depending centrally from said crossbars, the Vernier arranged on said axis below, said cross-bars having a deflected graduated portion, and the hinged or folding sights arranged between said parallel bars, at their ends, one of said sights having a sliding mirror, adapted to be projected beyond the normally upper end of said sight, substantially as set forth.

3. In an instrument of the character described, the combination of the parallel crossbars, the axis depending centrally from said bars, the Vernier arranged on said axis, the graduated co mpass-circle arranged below said Vernier, a transparent plate or portion interposed between said cross-bars and vernier, the bubble-glass, the needle playing in connection with said compass circle and the hinged or folding sights arranged between said parallel bars, at their ends, and adapted to fold flush with said axis, substantially as set forth.

JULES A. BIRSFIELD.

\Vitnesses:

CHAS. M. PRIEST, FRANK W. CYCHLAN.

IIO 

